1. Field
This invention relates to composite window coverings and to methods and apparatus for the manufacture of such coverings. The invention is particularly directed to the manufacture of full length pleated window coverings from physically similar remnant pieces of cellular (honeycombed) fabrics and the manufacture of full length window coverings having connected lengths of physically different window covering materials.
2. State of the Art
Expandable cellular fabric panels are commonly used as window coverings. Such window coverings permit light transmission and provide privacy, as desired. They are generally decorative, but also provide insulating barriers against heat transfer through window panes. In general, such fabric panels comprise a layer of a flexible sheet material, such as a polyester film, polyester impregnated paper or fabric. The sheet material is folded into individual tubular cells which are interconnected to form an elongate panel structure capable of bellows-like length adjustment. Each individual cell encloses an air pocket when the panel is stretched and suspended as a window covering. The air pockets serve as insulation. The interior and exterior surfaces of the panel structure may be made of materials having different properties, selected to meet specific use requirements. Cellular fabrics are sometimes referred to as "honeycomb" fabrics because the cells characteristically have hexagonal cross sections reminiscent of the individual cells of a honeycomb.
U.S. Pat. No. 4,019,554 discloses a thermal insulating curtain, especially for use in greenhouses. A plurality of superimposed tubular members are arranged uni-directionally to define a common slat-like partition between adjacent such members. Each of these tubular members, along its two opposite sides, has a folding crease to allow collapsing of the member, thereby to permit the entire curtain to either be collapsed in the manner of a blind or to be rolled up in the manner of a shade.
U.S. Pat. No. 4,288,485 discloses a collapsible and expandable tubular insulating curtain and a method of manufacture of such curtain. The curtain disclosed has rows of top to bottom interconnected tubes, with the tubes of adjacent rows bonded together.
U.S. Pat. Nos. 4,450,027, 4,603,072, and 4,631,108 each disclose a method and apparatus for fabricating cellular expandable insulation panels. The method and apparatus disclosed provide for folding a continuous thin film of flexible plastic material into a uniform, open faced tubular cell configuration and for heat setting the folds in permanent sharp creases. The method and apparatus further provide for the continuous stacking of successive lengths of the tubular film cells one on top of another on flat surfaces and adhering them together in the form of a neat, uniform, expandable panel of cellular configuration.
U.S. Pat. No. 4,795,515 discloses a method of making a series of expandable tubular polygons by simultaneously pleating and joining two adjacent sheets of fabric.
In practice, the construction and installation of window coverings from the cellular fabrics currently in use involves a significant amount of cutting. The resulting remnants are generally unsuitable for use and are discarded. As a consequence, a considerable portion of the investment made by fabricators for cellular fabric materials is wasted. There is a need for a method for salvaging this waste material.
There also remains a need for a method to produce window coverings of greater variety than now exists; notably coverings formed from connected lengths of cellular fabrics of different appearance or physical properties. Window covering sections having differing characteristics could then be selectively positioned fully or partially over selected portions of a window area.